Restless legs syndrome (RLS) is a medical condition that causes uncomfortable sensations in the legs, coupled with the urge to move them repeatedly. Because RLS is a clinically recognized disorder, there are few close synonyms for the term, but some do crop up in other contexts. For example, "akathisia" may be used to describe a similar compulsion to move one's limbs that is often a side effect of certain medications. "Restive" or "fidgety" may be used to describe someone who seems constantly restless or unable to sit still. However, none of these terms quite capture the full complexity of RLS or offer a precise substitute for it.